English
Le français
Türkçe
With the motor still in place, most of the key dimensions — shaft height, shaft diameter and length, the spacing between foot holes, overall length and the outer flange dimensions — can be taken with calipers and a tape measure. During measurement the machine must be isolated and locked off, as you will be working close to rotating parts.
Dimension list and method
| Dimension | IEC letter | How to take it |
|---|---|---|
| Shaft height | H | From the foot base to the shaft centre; measure from the foot contact surface to the top of the shaft and subtract the shaft radius |
| Shaft diameter | D | With calipers, on the part of the shaft not covered by the pulley or coupling |
| Shaft length | E | From the shaft shoulder to the shaft end; if a hub is fitted, its length helps |
| Foot hole spacing (across) | A | Between hole centres, opposite feet |
| Foot hole spacing (lengthwise) | B | Between the two hole centres on the same side |
| Shaft shoulder to front foot hole | C | From the shaft shoulder to the centre of the front foot hole |
| Overall length | L | From the shaft end to the rearmost point of the fan cover |
On flange-mounted motors
The outside diameter of the flange (P) is easy to measure. The diameter of the circle on which the bolt holes sit (M) is taken between the centres of two opposite holes. The spigot diameter (N), however, is usually hidden because the flange sits in the machine; it has to be confirmed from the mating recess on the machine side or from the manufacturer's drawing.
Common measuring mistakes
- Measuring the shaft diameter across the keyway
- Including the packing underneath when working out the shaft height
- Taking hole spacing from edge to edge
- Measuring overall length from the base instead of the fan cover
You can check the values you have taken against the dimension table in the DRG motor technical drawings. On a 132 frame, for example, the 5.5 kW, 4-pole cast iron frame model has a 38×80 mm shaft and an overall length of 438 mm; other models with similar values are in the shop listing.